硅酸盐学报

（Ba,Sr）TiO₃拉伸应变薄膜的介电响应

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于展波 ¹^,² , 马兴越 ¹^,² , 吴宗铄 ² , 高志昊 ¹^,² , 吴迪 ¹^,² , 杨玉荣 ¹^,²

硅酸盐学报 | 第14届无机非金属材料专题研讨会专题—研究论文 2025,53(4): 800-807

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硅酸盐学报 |第14届无机非金属材料专题研讨会专题—研究论文 2025 , 53 (4) : 800 -807

（Ba,Sr）TiO₃拉伸应变薄膜的介电响应

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于展波¹^,², 马兴越¹^,², 吴宗铄², 高志昊¹^,², 吴迪¹^,², 杨玉荣¹^,²

作者信息

^1．南京大学现代工程与应用科学学院，材料科学与工程系，南京 210093

^2．南京大学，固体微结构物理全国重点实验室，南京 210093

通讯作者:

吴迪（1974—），男，博士，教授；

杨玉荣（1980—），男，博士，教授。

作者简介:

于展波（2000—），男，硕士研究生。

Dielectric Response of (Ba,Sr)TiO₃ Thin Films under Tensile Strain

Zhanbo YU¹^,², Xingyue MA¹^,², Zongshuo WU², Zhihao GAO¹^,², Di WU¹^,², Yurong YANG¹^,²

Affiliations

^1.College of Engineering and Applied Sciences, Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, China

^2.National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China

Corresponding Author:

WU Di (1974-), male, Ph.D., Professor; E-mail: diwu@nju.edu.cn;

YANG Yurong (1980-), male, Ph.D., Professor. yangyr@nju.edu.cn

YU Zhanbo (2000-), male, Master candidate. E-mail: zhanboyu@smail.nju.edu.cn

出版时间: 2025-04-20 doi: 10.14062/j.issn.0454-5648.20240850

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摘要

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介电响应是铁电材料的重要物理性质之一，然而，铁电多畴结构的高频介电响应尚不明确。通过使用基于第一性原理的有效哈密顿量方法，研究了（Ba_0.8，Sr_0.2）TiO₃（BST_0.8）薄膜在1.55%面内拉伸应变下单畴结构和包含180°和90°畴壁的多畴结构的介电响应。动力学研究表明180°和90°畴壁都是稳定的，并表现出类似的动力学自发振荡。单畴结构的介电响应谐振峰主要出现在太赫兹范围内，改变外部电场的大小可以操纵BST_0.8中单畴结构介电响应的谐振峰频率。多畴结构的畴壁运动在低频的介电响应中占主导地位，并且180°和90°畴壁都具有一个与畴壁谐振有关的低频模式。本工作对BST_0.8单畴和多畴介电响应的研究结果对微波介质陶瓷的应用有推动作用。

关键词

多畴结构 / 介电响应 / 有效哈密顿量方法 / 第一性原理

Abstract

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Introduction

Frequency-dependent dielectric response is one of the important properties of ferroelectrics, reflecting the polarization response to high-frequency electric fields. Polarizations are closely related to ferroelectric domain structures, such as single domain, which represents the region with homogeneous polarizations direction. Ferroelectrics usually possess complex domain structures with domain walls (DWs) separating adjacent homogeneously polarized domains. DWs have attracted much attention during the past two decades due to their properties and potential for device designing. The related issues include DW motion, nonvolatile memory, topological defects, enhanced susceptibility, enhanced quality factor, low dielectric loss, and others. (Ba_0.8, Sr_0.2)TiO₃ (BST_0.8) is a ferroelectric usually with multi-domain structures. Previous work identified two typical types of domain walls (DWs), i.e., 90° DWs and 180° DWs. The enhancement of dielectric response in systems with 90° DWs is now well understood, and the behavior of dielectric response in multi-domain systems with 180° DWs remains unclear. Therefore, gaining insights into how 180° DWs affect the dielectric response can clarify the effects in multidomain systems.

Methods

We performed molecular dynamics simulations using the ALFE-H code with the first-principles-based effective Hamiltonian method to study the BST_0.8 system. All the calculations were performed in the NPT ensemble using the Evans-Hoover thermostat, and periodic boundary condition (PBC) along all three directions. To simulate the substrate, a uniform biaxial strain was fixed to the 1.55% in-plane strain. To analyze the multi-domain with different DWs, the simulations started with a self-constructed initial multi-domain polarization configuration. Subsequent 50 ps MD simulation was performed under chosen strains for structural relaxation. In the initial configuration, the magnitude of non-zero components of soft mode on each site was set to 0.1 Å, atomic occupations (alloying) were randomized, and unless otherwise specified, all other mode variables were set to zero. The trajectory of local mode averaged over the supercell during MD simulations was extracted to calculate the dielectric response. The 8 ns MD simulations were performed to obtain an autocorrelation function for any time t ranging from 0 to 1 ns by one step of 10 fs. The fast Fourier transformation (FFT) was performed to calculate the dielectric response. Then two uncoupled damped harmonic oscillators (DHOs) were used to fit the data of dielectric response.

Results and discussion

The dielectric response of single domain at 300 K with the different electric fields along [110] from 0 to 2 MV/cm was computed. The computational results can be well fitted with the model of two uncoupled DHOs. The real and imaginary parts of the predicted dielectric response at each chosen electric field both exhibit two peaks. As the electric field increases, the low-frequency mode with 300 GHz at zero field in the system gradually disappears, and a high-frequency mode of larger than 8 THz appears when electric field is larger than 1 MV/cm. The high frequencies modes of 3 THz at zero filed and 8 THz under 1 MV/cm shift towards higher frequencies as the electric field increases. In other words, the present simulations reveal that it is possible to manipulate the frequency of peaks in dielectric response via changing the magnitude of the external electric field.

The dielectric responses of multi-domain with 90° DWs and 180° DWs are further analyzed. According to the experimental PFM results, the multi-domain structures are simulated and the dielectric response through MD simulations is calculated. The analysis of the dielectric response of single domain structure and multi-domain structures shows that the single domain structures exhibit high-frequency peaks at > 300 GHz, whereas the multi-domain structures exhibit low-frequency peaks at 8 GHz and 120 GHz for 180° DWs system and at 10 GHz for 90° DWs system, revealing that there exists a low-frequency mode related to collective oscillation of DWs in multi-domain structures. In addition, the frequencies of peaks in multi-domain with DWs are in a gigahertz range, whereas the single domain structure exhibits peaks in a terahertz range. The contribution of DWs to the dielectric response primarily arises from the timescale of DWs motion, such as sliding or breathing, which differs significantly from the high-frequency vibrations of optical phonon modes. The vibrational frequency of DWs is much lower, with relaxation times in the order of nanoseconds, resulting in a response frequency in GHz range, which is far below the terahertz range of optical phonon modes. Therefore, DWs oscillations dominate the dielectric response at a low frequency. Moreover, multi-domain structure with 180° DWs exhibits a unique low frequency mode at 120 GHz, which is significantly different from single domain and 90° DWs system. In other words, multi-domain structures with 180° DWs and 90° DWs exhibit different dielectric responses. There exists a common low-frequency mode related to the oscillations of DWs in BST_0.8.

Conclusions

It was possible to manipulate the frequency of peaks in dielectric response of single domain through changing the magnitude of the external electric field. Domain walls oscillations dominated the dielectric response in a low frequency gigahertz range, whereas the single domain structures exhibited resonant peaks in a terahertz range. Moreover, multi-domain structures with different domain walls in BST_0.8 had different dielectric responses, but the both have a same low-frequency mode at 10 GHz related to the domain walls oscillations. The results of this study indicated the dielectric response behaviors of ferroelectrics induced in an external electric field and internal multi-domain configurations and provided the potential mechanisms and guidance for optimizing application performance.

Key words

multi-domain / dielectric response / effective Hamiltonian method / first-principles

引用本文

于展波, 马兴越, 吴宗铄, 高志昊, 吴迪, 杨玉荣. （Ba,Sr）TiO₃拉伸应变薄膜的介电响应. 硅酸盐学报, 2025 , 53 (4) : 800 -807 . DOI: 10.14062/j.issn.0454-5648.20240850

Zhanbo YU, Xingyue MA, Zongshuo WU, Zhihao GAO, Di WU, Yurong YANG. Dielectric Response of (Ba,Sr)TiO₃ Thin Films under Tensile Strain[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (4) : 800 -807 . DOI: 10.14062/j.issn.0454-5648.20240850

基金

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国家重点研发计划(2022YFB3807601; 2020YFA0711504)
国家自然科学基金(12274201; 52232001; 51721001; 52003117)

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2025年第53卷第4期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240850

接收时间：2024-12-31
首发时间：2026-10-22
出版时间：2025-04-20

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收稿日期：2024-12-31
修回日期：2025-02-18

基金

国家重点研发计划(2022YFB3807601; 2020YFA0711504)

国家自然科学基金(12274201; 52232001; 51721001; 52003117)

作者信息

^1．南京大学现代工程与应用科学学院，材料科学与工程系，南京 210093

^2．南京大学，固体微结构物理全国重点实验室，南京 210093

通讯作者:

吴迪（1974—），男，博士，教授；

杨玉荣（1980—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240850

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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